A UN report published in November 2014 was unable to specify how much money Islamic State militants were earning from looting and selling on Syrian and Iraqi antiquities.

Western diplomats estimate successful air strikes on refineries mean oil is no longer the main source of revenue for the jihadists.

In November, UN estimates put ISIL’s oil revenue at between 742,000 and 1.4 million euros per day.

States are also urged to stop vehicles from entering or leaving Islamic State-controlled regions, if they are suspected of involvement in smuggling.

The resolution outlined concern that the group and others “are generating income from engaging directly or indirectly in the looting and smuggling of cultural heritage items … to support their recruitment efforts and strengthen their operational capability to organise and carry out terrorist attacks.”

Ransom payments were assessed to raise between 84,000 and 108,000 euros daily. The resolution, then, called on “all Member States to prevent terrorists from benefitting directly or indirectly from ransom payments or from political concessions and to secure the safe release of hostages.”